Ruling out piriformis syndrome before diagnosing lumbar radiculopathy

Piriformis syndrome (PS), a rare cause of sciatica, is usually diagnosed only after excluding all other possibilities. But this principle is being challenged because of the number of patients with PS who have had ineffective lumbar decompressive surgery after positive findings on image study.

From 2001 to 2004, twelve patients with piriformis syndrome diagnosed by physical examination were retrospectively enrolled in this study. Indicators of piriformis syndrome include a positive Freiberg sign and local tenderness over the piriformis tendon. All patients received local injection of triamcinolone acetonide and lidocaine into the piriformis tendon. The course of diagnosis and treatment was reviewed retrospectively from patient records and patient recollections.

Of seven (58.3%) patients who had positive findings on computed tomography (CT) or magnetic resonance imaging (MRI) studies of the lumbar spine, four had previously undergone unsuccessful lumbar surgeries but were responsive to local injection and three received the injection first. Two of those three required no lumbar discectomy thereafter. However, one patient subsequently underwent lumbar decompression surgery because of failed response to the local injection. Three patients had negative CT or MRI findings, and two received no CT or MRI study. According to our diagnostic flowchart for PS, further lumbar surgery was unnecessary for eleven of the twelve patients at follow-up.

According to experience in this series, a Freiberg test and local injection should be performed first to rule out PS in patients with unilateral sciatica. If symptoms are relieved by local injection and further physical therapy for PS, unnecessary lumbar surgery can be avoided.